Processing of hides and stabilized tanning solution therefor



Patented Oct. 19, 1954 PROCESSING OF HIDES AND STABILIZED TANNING SOLUTIQN THEREFOR Friedrich Schmitt, Dusseldorf-Holthausen, and Rudi Heyden, Dusseldorf, Germany, assignors to Bonnie Fettchernie G. m. b. H., Dusseldorf,

Germa y No Drawing. Application August '25, 1951, Serial 'No. 246,508

2 Claims. (Cl. 8 --94.26)

This invention relates to tanning liquors and more particularly to tanning liquors which comprise as eilective tanning agents in combination chromium salts and sulfonated oils.

It has been customary to use tanning oils of this kind for tanning lighter animal skins, such as the skins of calves, goats, sheep, does, deer and chamois, as well as pig hides in order to produce soft leather to be used in the manufacture of gloves, wearing apparel, uppers for shoes, suede leather, and leather for technical purposes.

Some furs, such as rabbits and mouton or the more precious furs like mink, pole-cat, muskrat and others, like foals, were likewise tanned with the same agents, the method being one of rubbing or spreading,

In the combined tannin agents heretofore in use, it is customary to add a certain amount of salts, particularly sodium chloride, to the tanning liquors. The sulfonated oils, however, are instable in the presence of salts and will be salted out by chromium salts or sodium chloride forming a deposit.

This is a considerable disadvantage and reduces the usefulness of the existing tanning liquors; as a matter or fact, it sometimes renders them altogether useless.

It is the object of the present invention to overcome the above mentioned drawback by providing sulfonated tanning oils which are not subject to decomposition by the addition of salts and which will serve as useful tanning agents remaining eflective for a long time.

It is another object of the invention to provide tanning agents which are particularly useful in the tanning of skins and hides for purposes Where soft quality and rich touch are desired.

Other objects and advantages of the present invention will become apparent from the following specification.

The inventors have found that sulfonated tan- Illl'lg oils can be prepared which are stable in the presence of a chromium salt or several chromium salts and other mineral salts by adding to the oils water-soluble derivatives of polyalkylene oxide waxes; the compounds in question are derivatives of waxes of the type mentioned which have a molecular weight of at least 2000 and are combined with one or more radicals of the aliphatic, alicyclic or aromatic type, or with radicals of combined aliphatic-alicyclic, aliphatic-aromatic or similar nature. Said radicals should have at least 4 carbon atoms and are connected to the poly- "alkylene oxide component by means of oxygen,

sulfur or nitrogen, more particularly also by means of ester and acid amide groups.

A preferred polyalkylene oxide wax to be used in accordance with the invention is polyethylene oxide wax, but polymerization products of other alkylene oxides may likewise be used. In order to obtain said derivatives, ethylene oxide may for instance be reacted in the presence of a catalyst on the desired aliphatic, alicyclic, aromatic etc. compound, having hydroxyl, carboxyl, mercapto, amino or acid amide groups in the molecule, the reaction being allowed to continue until the desired stage of condensation i. e. the desired size of the molecule will have been reached.

As starting materials we may use, for example, butyl alcohol, octyl alcohol, octyl mercaptan,

dodecyl amine, cyclohexyl alcohol, cyclohexyl' amine, naphthene alcohols, benzyl alcohol, ar-

tetralol, a mixture of first'runnings of fatty acids C1-C9, naphthene acids, oleic acid, lauric acid amide, alkylbenzene sulfonic acid amide, etc.

Another way for obtaining the desired others or esters consists of etherifying or esterifying polyethylene oxide wax with the above named hydroxy compounds or carboxylic acids, respectively.

By sulfonated oils for the purpose of manufacturing the tanning liquors to be used we understand the sulfonation products of animals, vegetable or mineral oils or mixtures thereof generallyknown in the art, for instance: turkey red. oil, sulfonated neats-foot oil, sulfonated sperm oil or fish oil, sulfonated vegetable oils, such as poppy seed or sunflower oils, and the sulfonation products of natural or synthetic mineral oils,

such as mixtures of straight chain or branched chain alkyl, aryl, or alkylaryl sulionic acids of high molecular weight or neutralization products thereof. If desired, a certain amount of unsulfonated oils may be mixed to the sulfonated oils.

By chromium salts for tanning liquors we understand chrome alums or other known chromium salts used for producing tanning liquors or extracts in the art of chrome tanning.

The polyethylene oxide derivatives to be used according to the present invention are solid watersoluble compounds of waxy consistency which are soluble in the tanning oils or capable of forming a homogeneous dispersion therewith. They stabilize the oils against the salt-ing-out caused by electrolytes. Depending on the particular tanning oil to be used, the amount of added stabilizer varies. In general, quantities of 10 to 50% calculated on the weight of tanning oil should be added.

Example 1 20 parts by weight of a leather oil consisting of 50% turkey red oil, 45% spindle oil and 5% of sulfonated oleyl-alcohol are stirred, while being heated, with parts of a polyethylene oxide ester obtained by partial esterification of polyethylene oxide, having a molecular weight of 9000, with a mixture of first runnings of fatty acids of a chain length of C4 to C9, the said acids being oxidation products of parafiin. To the homogeneous mixture are added 28 parts of water and then, gradually, 30 parts of a 33% sodium chloride solution and 12 parts of a chrome alum solution of alkaline reaction are stirred into the mixture.

A stable tanning liquor is thus obtained which may be used successfully for tanning furs or soft leathers.

Example 2 A mixture consisting of 38 parts of spindle oil (viscosity 56 Engler at 20 0.), 34 parts of mixed unsaturated fatty acids, obtained from sperm oil and sulfonated thereafter by treatment with 96% sulfuric acid, and 4 parts of the sodium salt ofsulfonated oleic acid is mixed with a polyethylene oxide wax ester, liquefied by heating. The said ester is the product of complete esterification of polyethylene oxide, having an average molecular weight of 7500, with stearic acid. The mixture is being stirred until it has cooled down to room temperature. A product of pasty consistency is obtained thereby. Into one part of this paste 2.6 parts of a tanning solution containing per liter 70 grams of sodium chloride and 36 grams of a commercial chromium tanning salt with a Cl'zOs contents of 25% are stirred.

The emulsion thus obtained is very stable and is used for tanning furs.

Example 3 100 parts of a leather oil consisting of 47 parts of sulfonated fish oil, 47 parts of neats-foot oil and 6 parts of the sodium salt of oleyl sulfonic acid are mixed with 10 parts of the paste obtained according to Example 2. The mixture is emulsified in 5 times its amount of water and added to a chrome tanning solution; the addition may be made before or after having neutralized the chrome solution with sodium carbonate.

The stable solution thus obtained is absorbed uniformly by the leather and imparts thereto a particularly soft and rich touch.

Example 4 65 parts of the oil mixture according to Example 2, containing spindle oil, sulfonated sperm oil and oleyl sulfonate, are mixed with 35 parts of an ester obtained by partial esterification of polyethylene oxide wax, having a molecular weight of 5500, with the mixture of fatty acids contained in coconut oil and having a chain comprising 9-11 carbon atoms. One part of the paste obtained is stirred with 6 parts of a solution containing grams sodium chloride and 60 grams of commercial chrome tanning salt per liter.

A stable solution is thereby obtained which is excellently suited for tanning purposes.

While we have described preferred embodiments of our invention, it will be understood that We do not limit ourselves in any particulars.

Obviously, various modifications of our invention may be made within the scope of the inven tion as disclosed and claimed in the following claims.

We claim: 7

1. A stabilized aqueous tanning solution comprising a sulfonated oil selected from the group consisting of neats foot oil, sperm oil, and vegetable oil, at least one chrome tanning agent, sodium chloride, and about 10-50% by Weight based on said oil of a member of the group consisting of carboxylic acid esters and ethers having a chain of at least four carbon atoms of a polyethylene oxide wax having a molecular weight of 2000 to 9000.

2. A process of tanning animal hides comprising subjecting said hides to the action of a stabilized aqueous tanning solution comprising a sulfonated oil selected from the group consisting of neats foot oil, sperm oil, and vegetable oil, at least one chrome tanning agent, sodium chloride, and about 10-50% by weight based on said oil of a member of the group consisting of carboxylic acid esters and ethers having a chain of atleast four carbon atoms of a polyethylene oxide Wax having a molecular weight of 2000 to 9000.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,949,384 Weyner Feb. 27, 1934 1,970,578 Schoeller Aug. 21, 1934 2,235,098 Brandt Mar. 18, 1941 2,425,828 Retzsch et al Aug. 19, 1947 2,456,587 Koppenhoefer Dec. 14, 1948 2,496,641 Schiller et al. Feb. 7, 1950 2,555,684 Decastro et a1 June 5, 1951 OTHER REFERENCES Rayon Textile Monthly, Dec. 1947, page 118 (670). 

1. A STABILIZED AQUEOUS TANNING SOLUTION COMPRISING A SULFONATED OIL SELECTED FROM THE GROUP CONSISTING OF NEAT''S FOOT OIL, SPERM OIL AND VEGETABLE OIL, AT LEAST ONE CHROME TANNING AGENT, SODIUM CHLORIDE, AND ABOUT 10-50% BY WEIGHT BASED ON SAID OIL OF A MEMBER OF THE GROUP CONSISTING OF CARBOXYLIC ACID ESTERS AND ETHERS HAVING A CHAIN OF AT LEAST FOUR CARBON ATOMS OF A POLYETHYLENE OXIDE WAX HAVING A MOLECULAR WEIGHT OF 2000 TO
 9000. 